// Test that tailable cursors work correctly with skip and limit.
(function() {
    "use strict";

    // Setup the capped collection.
    var collname = "jstests_tailable_skip_limit";
    var t = db[collname];
    t.drop();
    db.createCollection(collname, {capped: true, size: 1024});

    t.save({_id: 1});
    t.save({_id: 2});

    // Non-tailable with skip
    var cursor = t.find().skip(1);
    assert.eq(2, cursor.next()["_id"]);
    assert(!cursor.hasNext());
    t.save({_id: 3});
    assert(!cursor.hasNext());

    // Non-tailable with limit
    var cursor = t.find().limit(100);
    for (var i = 1; i <= 3; i++) {
        assert.eq(i, cursor.next()["_id"]);
    }
    assert(!cursor.hasNext());
    t.save({_id: 4});
    assert(!cursor.hasNext());

    // Non-tailable with negative limit
    var cursor = t.find().limit(-100);
    for (var i = 1; i <= 4; i++) {
        assert.eq(i, cursor.next()["_id"]);
    }
    assert(!cursor.hasNext());
    t.save({_id: 5});
    assert(!cursor.hasNext());

    // Tailable with skip
    cursor = t.find().addOption(2).skip(4);
    assert.eq(5, cursor.next()["_id"]);
    assert(!cursor.hasNext());
    t.save({_id: 6});
    assert(cursor.hasNext());
    assert.eq(6, cursor.next()["_id"]);

    // Tailable with limit
    var cursor = t.find().addOption(2).limit(100);
    for (var i = 1; i <= 6; i++) {
        assert.eq(i, cursor.next()["_id"]);
    }
    assert(!cursor.hasNext());
    t.save({_id: 7});
    assert(cursor.hasNext());
    assert.eq(7, cursor.next()["_id"]);

    // Tailable with negative limit is an error.
    assert.throws(function() {
        t.find().addOption(2).limit(-100).next();
    });

    // Tests that a tailable cursor over an empty capped collection produces a dead cursor, intended
    // to be run on both mongod and mongos. For SERVER-20720.
    t.drop();
    db.createCollection(t.getName(), {capped: true, size: 1024});

    var cmdRes = db.runCommand({find: t.getName(), tailable: true});
    assert.commandWorked(cmdRes);
    assert.eq(cmdRes.cursor.id, NumberLong(0));
    assert.eq(cmdRes.cursor.ns, t.getFullName());
    assert.eq(cmdRes.cursor.firstBatch.length, 0);

    // Test that the cursor works in the shell.
    assert.eq(t.find().addOption(2).itcount(), 0);
    assert.writeOK(t.insert({a: 1}));
    assert.eq(t.find().addOption(2).itcount(), 1);
})();